JPH027875A - Ultrasonic oscillator and driver having this oscillator - Google Patents

Abstract

PURPOSE:To oscillate an upper pedestal in any direction by controlling the synthesization of generated oscillation with a platelike piezoelectric laminate body and piezoelectric elements provided there. CONSTITUTION:An oscillator 20 is composed of a piezoelectric laminate member 25 laminated in numerous pieces of platelike piezoelectric elements 21, a piezoelectric element 22, an upper pedestal 23 and a bottom pedestal 24. This piezoelectric elements 21 are laminated into a piezoelectric laminate member 25 so that the direction of polarization may alternately be opposite. The upper pedestal 23 is made of metal, etc., and adhered to the upper surface of the piezoelectric laminate member 25. In the center of the upper surface of the upper pedestal 23 a dome-shaped projection 26 is provided. A piezoelectric laminate body is thus composed of this piezoelectric laminate member 25, the upper pedestal 23 and the bottom pedestal 24. In this way, when the piezoelectric laminate body and the piezoelectric element 22 fitted to it are oscillated, the generated oscillations in longitudinal and transverse directions are synthesized and its synthesized condition is controlled. As a result, the material point on the oscillator performs an elliptical oscillation or a tilting reciprocating oscillation of arbitrary size and aspect and the movable member moves in the specified direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic vibrator using an electro-mechanical transducer such as a piezoelectric element as a vibration source, and a drive device having this vibrator.

[Prior Art] Recently, ultrasonic motors have been in the spotlight as a new motor to replace electromagnetic motors. This ultrasonic motor is not only new in principle, but also has the following advantages over conventional electromagnetic motors.

■ Thin, lightweight, and compact.

■ Low speed and high torque can be obtained without gears.

■ The component configuration is simple and highly reliable.

■ There is no exchange of magnetic influence.

■ There is no backlash and positioning is easy.

In order to take advantage of these advantages, various applied techniques are being researched.

Ultrasonic motors can be broadly divided into annular and linear types. 14 to 17 are diagrams showing conventional examples of linear type ultrasonic motors.

FIG. 14 is a diagram showing a first conventional example. When the Langevin type piezoelectric vibrator 1 on the left side of the figure is vibrated and the tip of the horn 2 is brought into contact with the propagation rod 3 made of an elastic body, the propagation rod 3
A bending traveling wave is generated.

This bending traveling wave propagates rightward in the propagation rod 3 as shown by the solid arrow. This traveling wave then excites the Langevin type piezoelectric vibrator 5 via a similar horn 4 attached to the right end of the propagation rod 3. At this time, select L and R in the figure appropriately and perform impedance matching.
All the energy of the traveling wave mentioned above is absorbed. In this way, the traveling wave will always travel steadily from the left to the right.

Now, when the slider 6 is held in pressure contact with the surface of the propagation rod 3 where such a bending traveling wave is generated with a certain pressing force, the slider 6 moves to the left in the figure as shown by the solid arrow H. go.

FIG. 15 is a perspective view schematically showing the relationship between the bending traveling wave of the propagation rod 3 and the slider 6. In the figure, 3A is an elastic body corresponding to the propagation rod 3, and 6A is a moving body corresponding to the slider 6. As shown in FIG. 15, the mass point P of the elastic body 3A draws an elliptical locus. Therefore, the moving body 6 is placed on the elastic body 3A, which is drawing a counterclockwise elliptical locus in this figure.
When A is brought into contact with a predetermined pressure, the movable body 6A is driven in a direction opposite to the traveling direction of the traveling wave, that is, to the left in the figure. Note that if the propagation direction of the traveling wave is reversed, the moving body 6A is driven rightward in the figure.

FIG. 16 is a diagram showing the configuration of another conventional example.

A vibrating piece 8 is attached to the tip of the Langevin type vibrator 7. The tip of the vibrating body 8 is in contact with the slider 6B with a constant pressing force while being inclined at a predetermined angle θ with respect to the normal to the surface of the slider 6B.

When an AC voltage having the same frequency as the natural frequency of the Langevin type vibrator 7 is applied from the AC power supply 9 to the Langevin type vibrator 7, the Langevin type vibrator 7 performs longitudinal vibration.

At this time, since the tip of the vibrating piece 8 is in contact with the slider 6B at a predetermined angle θ, lateral vibration is also performed.

By combining these vibrations, the tip of the vibrating element 8 draws an elliptical locus. The slider 6B thus moves to the left as shown by the arrow in the figure.

FIG. 17 is a diagram showing yet another conventional example.
135278 shows the configuration of a vibrator disclosed in No. 135278. Piezoelectric elements 11 are provided on both sides of the rectangular conductive vibrator 10. ．． 12 is glued. This piezoelectric element 11
．． Lead terminals A and B for voltage application are drawn out from 12, and a ground terminal E is also drawn out from vibrator 10. The shape of the vibrator 10 is such that the resonance frequency of the longitudinal vibration and the resonance frequency of the flexural vibration of the vibrator 10 match. Thus, when an AC voltage having the above resonance frequency is applied to the lead terminals A and B with a constant phase difference, the mass point on the end surface S of the vibrator 10 performs an elliptical motion. Therefore, when the slider 6C is pressed against the end surface S with a constant force, the slider 6C moves in the direction of the arrow HH in the figure. This direction of movement is determined by the phase difference between the voltages applied to terminals A and B.

[Problems to be Solved by the Invention] The basic principle of the ultrasonic motor shown in FIGS. 14 to 17 is to transmit the energy of the elliptical locus motion at the mass point of the vibrator to the moving body (slider) by friction. There is.

In the first conventional example shown in FIG. 14, traveling waves must be generated throughout the propagation ring 3, which is inefficient and
There was a problem that the entire device became large. Further, in the second conventional example shown in FIG. 16, the advancing direction of the slider 6B is limited to one direction, and, like the first conventional example, there is a problem that the entire device becomes large. Furthermore, in the third conventional example shown in FIG. 17, the vibration output is obtained by piezoelectric elements 11 and 12 bonded to both sides of the vibrator 10, so it is difficult to secure a large force for moving the slider 6C. Have difficulty. If the number of piezoelectric elements 11 and 12 bonded to the side surface of the vibrator 10 is increased in order to obtain a larger vibration output, there is a drawback that the device becomes larger accordingly. Furthermore, the conventional example shown in FIG. 17 attempts to generate elliptical vibration by combining the longitudinal vibration and flexural vibration of the vibrator 10, but if both vibrations are not in a resonant state, a large output will be generated. I can't get it.

Therefore, it is necessary to match the resonance frequency of longitudinal vibration and the resonance frequency of flexural vibration. For this reason, the shape of the vibrator 10 must be determined by trial and error, which requires a great deal of labor and is not easy to manufacture.

Therefore, the purpose of the present invention is to be compact, have high energy conversion efficiency, and be able to extract large vibration output.
An object of the present invention is to provide an ultrasonic vibrator that can reversibly move a driven object when used as a linear motor, has fewer design restrictions, and is easy to manufacture, and a drive device having this vibrator.

[Means for Solving the Problems] Therefore, the present invention has taken the following measures in order to solve the above problems and achieve the objectives. (1) A piezoelectric laminate formed by laminating a plurality of plate-shaped piezoelectric elements, with an upper stand for extracting vibration output on one end face and a lower stand as a substrate on the other end face, and this piezoelectric laminate The apparatus includes a piezoelectric element provided on a side surface of the body, and means for controlling the combination of vibrations generated from the piezoelectric laminate and the piezoelectric element to vibrate the upper table in an arbitrary direction.

(2) The piezoelectric element is provided on the side surface of the piezoelectric laminate so as to connect the upper and lower bases.

(3) The piezoelectric element is provided only on the side surface of the lower stand or the upper stand.

(4) Consists of the ultrasonic transducer of (1), (2), or (3) above, and a movable member that contacts the top of the ultrasonic transducer, and is configured to move this movable member in any plane direction. It was configured as follows.

[Function] ~ By taking the above measures, the following effects are exhibited. When the piezoelectric laminate and the piezoelectric element attached to the piezoelectric laminate are vibrated, the generated vertical and lateral vibrations are combined, and the combined state is controlled, so that the mass point on the vibrator is Elliptical vibration or inclined reciprocating vibration of arbitrary size and mode is performed. When the movable member is brought into contact with the top surface of the vibrator, the movable member moves in a predetermined direction. In this case, since a laminated piezoelectric actuator is used as the main vibration source, it is possible to obtain essentially a large mechanical output, and the frequency of the drive power source does not have to be matched to the natural frequency of the elastic body as in the conventional case. Since a large mechanical output can also be obtained, it may be driven non-resonantly, so there are fewer restrictions on design and it is easier to manufacture.

[First Embodiment] FIGS. 1 to 5 are diagrams showing the configuration of a first embodiment of the present invention, and FIG. 1(a) is a perspective view of an ultrasonic elliptical transducer, and FIG.
b) is a top view of the same vibrator.

The vibrator 20 includes a piezoelectric laminate member 25 formed by laminating a large number of plate-shaped piezoelectric elements 21, a piezoelectric element 22, an upper stand 23, and a lower stand 24. The piezoelectric element 21.2
2 has electrodes attached to both sides of piezoelectric ceramics such as PZT by sputtering with silver or Ni or plating with N1, and lead wires for grounding and voltage application are connected to these electrodes. . Several to several dozen pieces of the piezoelectric elements 21 are stacked so that their polarization directions are alternately reversed, and are bonded and laminated using an adhesive such as epoxy to form a piezoelectric laminate member 25.

The upper stand 23 is made of metal such as stainless steel or ceramic material such as alumina, and is a square plate having a predetermined thickness. This upper stand 23 is adhered to the upper surface of the piezoelectric laminate member 25. A hemispherical protrusion 26 is provided at the center of the upper surface of the upper stand 23.
is provided.

The lower base 24 is made of the same material as the upper base 23 and is bonded to the lower surface of the piezoelectric laminate member 25. Further, a screw hole (not shown) is formed in this lower stand 24 so that it can be easily attached to a base (not shown). The piezoelectric laminated member 25 has an upper stand 23. A piezoelectric laminate is constituted by the lower base 24°.

The electrodes connected to the respective piezoelectric elements 21 constituting the piezoelectric laminated member 25 are commonly connected every other layer, and one of the commonly connected electrodes is connected to the terminal A via a lead wire for voltage application, and the other is grounded via a grounding lead wire.

As shown in FIG. 1(b), the piezoelectric element 22 consists of a pair of piezoelectric elements 22a and 22b, which are placed on both sides of the piezoelectric laminate so that they face each other and have polarization directions in the same direction. It is adhered to via an insulating member (not shown). The electrodes on the bonding surface side of the piezoelectric elements 22a and 22b are grounded, and the electrodes on the outer surface side are commonly connected to terminal B via a lead wire for voltage application.

FIG. 2 is a diagram showing the configuration of a drive circuit for vibrating the vibrator 20. Reference numeral 30 denotes an AC power supply that outputs an alternating current of frequency f, and the output of this power supply 30 is supplied to a phase shifter 31 . It is applied to terminal B via power amplifier 32, and on the other hand to terminal A via power amplifier 33.

The phase shifter 31 is capable of shifting the phase of the alternating current output from the alternating current power supply 30 from 0 to 360 degrees. power amplifier 3
2.33 is for amplifying the AC power from the AC power supply 30 or the phase shifter 31.

Next, the operation of the vibrator 20 of this embodiment configured as described above will be explained with reference to FIGS. 3 to 5. When the alternating current of frequency f from the alternating current power source 30 is amplified by the power amplifier 33 and applied to the terminal A, the vibrator 20 is activated as shown in FIG.
) Perform longitudinal vibration as shown. The resonant frequency fe of this 1/4 wavelength resonance of longitudinal vibration is a sufficiently higher frequency than the electrical input frequency. That is, the above-mentioned longitudinal vibration is vibration due to non-resonance. On the other hand, the alternating current from the alternating current power supply 30 is supplied to the phase shifter 3.
When the phase of the vibrator 20 is shifted in the range of 0 to 360' by the power amplifier 32 and applied to the terminal B, the vibrator 20 causes transverse vibration as shown in FIG. 3(b). Perform bending vibration. At this time, the resonant frequency fb of the 1/4 wavelength resonance in the bending vibration is made to match the electrical input frequency to perform resonance driving.

When the above two vibrations are simultaneously excited and phase shift control is performed, the protrusion 26 will draw various trajectories as shown in FIGS. 4(a) to 4(i).

When using the vibrator 20 as a linear motor, (c)
, (g) can be obtained.

Furthermore, by changing the amplification factors of the power amplifiers 32 and 33, it is possible to change the magnitudes of the components v and u of the elliptical locus shown in FIG.

FIG. 6 is a perspective view showing a modification of the vibrator 20. In this modification, the piezoelectric element 2 of the vibrator 20 shown in FIG.
Whereas the piezoelectric elements 2a and 22b were adhered to the entire side surface of the piezoelectric laminate in a sealed state, the piezoelectric elements 22a and 22b were attached to an upper stand 23 and a lower stand 24 having an area larger than the area of the laminated surface of the laminated member 25. This is an example of bonding as if bridging the two. Even in this case, the vibrator 20 operates in the same manner as the vibrator 20 shown in FIG.

FIGS. 7(a) and 7(b) show other modified examples.

This modification is an example in which a square column-shaped lower table 24 made of a metal such as stainless steel or a ceramic material such as alumina is used, and piezoelectric elements 22a and 22b are bonded to the side walls of the lower table. This modification also operates in substantially the same manner as the vibrator 20 shown in the first diagram.

Note that in the above embodiment, the piezoelectric element 22a.

Although an example is shown in which a single plate is used as the piezoelectric element 22b, a large number of piezoelectric elements 22 may be laminated, for example, in order to increase the output of bending vibration. In this case, it is possible to obtain a large displacement even if the bending vibration shown in Fig. 3(b) is generated non-resonantly, so that the longitudinal vibration shown in Fig. 3(a) and the It is possible to generate the bending vibration shown in FIG. 3(b) without resonance. Further, as the piezoelectric laminate member 25, a plate-shaped piezoelectric element 2 is used.
1 is bonded with an adhesive such as epoxy resin, but electrodes such as platinum are printed on both sides of the green sheet,
It may also be a piezoelectric laminate member made by integrally firing after laminating and pressing.

FIGS. 8(a) to 8(d) are diagrams showing the configuration of a drive device using the vibrator 20 described above. As shown in FIG. 8(a), a plate-shaped slider 40 is brought into contact with the protrusion 26 of the vibrator 20 with a constant pressing force. In this case, as a means for pressing the slider 40 against the protrusion 26 with a constant force, a suppressing mechanism 41 including rollers and a spring may be used as shown in FIG. 8(b). If such a suppression mechanism 41 is used, the slider 40 will be able to move the vibrator 20
It becomes possible to move smoothly as shown by the arrow while being pressed with a constant force against. Moreover, the slider 40 is
A groove 42 having a U-shaped cross section as shown in FIG. 8(c) is provided in the part that presses against the groove 6, and the protrusion 26 engages with the inner bottom surface of the groove 42 as shown in FIG. 8(d). If they are aligned, the slider 40 can be moved straight due to the guide action of the groove 42.

A piezoelectric laminate and a piezoelectric element 22 attached to this piezoelectric laminate
a and 22b, the generated vertical and horizontal vibrations are combined, and the combined state is controlled, so that the mass point on the vibrator 10 can generate elliptical vibration or vibration of any size and form. Performs tilt reciprocating vibration. Therefore, when a movable member is brought into contact with the upper surface of the vibrator 10, the movable member moves in a predetermined direction. In this case, since a laminated piezoelectric actuator is used as the main vibration source, it is possible to obtain essentially a large mechanical output, and the frequency of the drive power source does not have to be matched to the natural frequency of the elastic body as in the conventional case. Since a large mechanical output can also be obtained, it may be driven non-resonantly, so there are fewer restrictions on design and it is easier to manufacture.

[Second Embodiment] FIGS. 9(a) and 9(b) are diagrams showing a second embodiment of the present invention,
(a) is a perspective view of an ultrasonic elliptical transducer, and (b) is a top view of the same transducer. Note that the same parts as those of the ultrasonic elliptical vibrator shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. This embodiment differs from the first embodiment in a pair of piezoelectric elements 22a.

Another pair of piezoelectric elements 51 (
51a and 51b) were adhered to the other two sides of the piezoelectric laminate. Note that the piezoelectric elements 51a, 51
One of the electrodes b is connected to the terminal B' via a lead wire for voltage application, and the other is grounded via a lead wire for grounding.

FIG. 10 is a diagram showing the configuration of a circuit for vibrating the vibrator 50. The output from the phase shifter 31 is branched into two,
They are connected so that power can be amplified by power amplifiers 32 and 32'. Power amplifier 32 is connected to terminal B, and power amplifier 32' is connected to terminal B'. Thus, the alternating current of frequency f from the alternating current power source 30 is transmitted through the phase shifter 31.
After the required phase shift (0 to 360°) is performed by the power amplifier 32, 32', the power is amplified and the terminals B,
B' through piezoelectric elements 22a, 22b and 51a
51b.

FIG. 11 is a perspective view showing the vibrator 50 and slider 52 shown in FIG. 9. When a voltage is applied to terminal A, longitudinal vibration as shown in FIG. 3(a) occurs in the vibrator 50 in the Z-axis direction shown in FIG. 9. Further, when a voltage is applied to terminal B, bending vibration as shown in FIG. 3(b) occurs in the vibrator 50 in the X-axis direction shown in FIG. 9. Furthermore, when a voltage is applied to terminal B', the oscillator 50 has a state shown in FIG.
The pen pudding vibration as shown in b) is caused by Y shown in Fig. 9.
Occurs in the axial direction.

The feature of the vibrator 50 of this embodiment is that it can generate an elliptical locus motion that is a combination of the above three vibrations, and that it can be controlled so that the plane containing the elliptical locus coincides with any plane containing the Z-axis. This is possible. For example, power amplifier 3
When the amplification degree of the power amplifier 2' is set to 0 and the amplification degree of the power amplifiers 32 and 33 is set to a certain value (direct) and a voltage is applied to each terminal, the protrusion 26 will move as shown in FIG. 4 in the X-Z plane shown in FIG. (
The trajectory shown in a) to (i) will be drawn. Further, the amplification degree of the power amplifier 32 is set to "0", and the power amplifier 3
When a voltage is applied to each terminal with the amplification degree of 2' and 33 set to a certain value, the protrusion 26 follows a trajectory as shown in FIGS. 4(a) to (i) in the Y-Z plane shown in FIG. I will draw it. Therefore, by appropriately adjusting the amplification degree of the power amplifiers 32, 32', the elliptical locus of the protrusion 26 can be made to coincide with any plane including the Z-axis. As a result, the slider 52, which is being pressed by the protrusion 26 with a predetermined force, is
It can be moved in any direction within the Y plane. Other than the above points, the same operation and effect as the first embodiment is achieved.

FIGS. 12 and 13 are diagrams showing modifications of the second embodiment described above, and are modifications having the same meaning as the modifications of the first embodiment (FIGS. 6 and 7). That is, in the example of FIG. 12, piezoelectric elements 22a, 22b and 51a,
51b is bonded in such a manner as to bridge the upper and lower bases 23 and 24, which have an area larger than the area of the laminated surface of the piezoelectric laminate member 25. Further, in the example shown in FIG. 13, the lower table 24 is made of a square prism, and a piezoelectric element 22a is attached to the side surface of the lower table 24.
, 22b and 51a, 51b are bonded together.

In addition, in the second embodiment described above, when the frequency f for driving each vibrator is made to match the longitudinal vibration frequency fe and the bending vibration frequency fb, if the frequency is in the audible range, this vibrator becomes a noise source to humans. becomes. Therefore, the frequency fe.

It is desirable to design the vibrator so that fb is in the ultrasonic range, that is, 20 kHz or higher.

It should be noted that the present invention is not limited to the above-described embodiments and modified examples, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, it is compact, has good energy conversion efficiency, can extract a large vibration output, and when used as a linear motor, can reversibly move an object to be driven. It is possible to provide an ultrasonic transducer that has fewer of the above limitations and is easy to manufacture, and a drive device having this transducer.

[Brief explanation of the drawing]

1(a)(b) to FIG. 8(a) to (d) are diagrams showing a first embodiment of the present invention, and FIG. 1(a)(b) is a perspective view of a vibrator and 2 is a configuration diagram of the drive circuit of the vibrator, FIGS. 3(a) and 3(b) are schematic side views showing the operating modes of the vibrator, and FIGS. 4(a) to (i) are schematic diagrams of the drive circuit of the vibrator. Figure 3 (a)
A diagram showing the locus of the protrusion when the operation modes shown in (b) are combined, FIG. 5 is a diagram showing the length and components of the elliptical locus, and FIG. 6 is a perspective view showing a modification of the same vibrator. Figure 7 (a
)(b) is a perspective view showing another modification of the same vibrator, and FIGS. 8(a) to (d) are diagrams showing the configuration of a drive device using the same vibrator. Figures 9(a)(b) to 13(a)(b)
) is a diagram showing a second embodiment of the present invention, and FIG. 9(a)
(b) is a perspective view and a top view of the vibrator, FIG. 10 is a configuration diagram of the drive circuit of the vibrator, FIG. 11 is a perspective view of the slider and vibrator, and FIG. 12 is a modification of the vibrator. FIGS. 13(a) and 13(b) are perspective views showing other modifications of the vibrator. 14 to 17 are diagrams showing a conventional ultrasonic linear motor, FIG. 14 is a diagram showing the configuration of a conventional ultrasonic linear motor, and FIG. 15 is a diagram showing a traveling wave generated in an elastic body of the conventional example. FIG. 16 is a diagram showing the configuration of another conventional example, and FIG. 17 is a diagram showing the configuration of still another conventional example. 1.5, 20.50... vibrator, 6, 40.4152
-7. Rider, 21, 22a, 22b, 51a. 5]-b...Piezoelectric element, 23...Upper stand, 24...
Lower stand, 25... Piezoelectric laminate member, 26... Projection, 3
0... AC power supply, 31... Phase shifter, 32.32'
, 33...power amplifier.

Claims (4)

[Claims] (1) A piezoelectric laminate formed by laminating a plurality of plate-shaped piezoelectric elements, with an upper stand for extracting vibration output on one end face and a lower stand as a substrate on the other end face, and this piezoelectric laminate A superstructure characterized by comprising: a piezoelectric element provided on a side surface of the body; and means for controlling the synthesis of vibrations generated from the piezoelectric laminate and the piezoelectric element to vibrate the upper table in an arbitrary direction. Sound wave vibrator. (2) The ultrasonic transducer according to claim 1, wherein the piezoelectric element is provided on a side surface of the piezoelectric laminate so as to connect the upper stand and the lower stand. (3) The ultrasonic transducer according to claim 1, wherein the piezoelectric element is provided only on a side surface of the lower stand or the upper stand. (4) The ultrasonic transducer according to claim 1, 2 or 3, and a movable member that contacts the top of the ultrasonic transducer, the movable member being configured to move in any plane direction. A drive device having an ultrasonic vibrator, characterized in that: